@Extreme_Boky, ahh, I see. Yes, that would have explained the symptoms (except I guess the high CLR line).
But for now, my uncle is indeed Bob.
I soldered in all the flying leads (which took ages), attached the faceplate, and... Bob's still my uncle. 🙂
It's time I took ZM's advice: be happy.
Cheers,
Jeff.
But for now, my uncle is indeed Bob.
I soldered in all the flying leads (which took ages), attached the faceplate, and... Bob's still my uncle. 🙂
It's time I took ZM's advice: be happy.
Cheers,
Jeff.
Well done, that's indeed an achievement; the schematics, board, case and machining... congrats.
So, how does it sound??? I found ACA to be outstanding as a headphone amplifier. Was wondering if you can give us some impressions...
I have the same opinion. How did you set it up?.
Maybe we could comment on the ACA thread 😉
Thanks!
Yes, I am also driving my headphones directly from the speaker terminals but I wanted to know if you had used any type of resistance in series.
I added a TRS on the front of the amplifier. I hope to put photos in a few days. 😉
My problem at the moment is a constant HUM and I have not been able to identify what is due. 😡
PS. Sorry for off topic
Yes, I am also driving my headphones directly from the speaker terminals but I wanted to know if you had used any type of resistance in series.
I added a TRS on the front of the amplifier. I hope to put photos in a few days. 😉
My problem at the moment is a constant HUM and I have not been able to identify what is due. 😡
PS. Sorry for off topic
So how's it sound?
I compared it to 2 other DIY builds: a Bottlehead SEX with some modifications (no CCS) and a Torpedo 3 clone (with tube and output stage CCSes). They were all built by me, so no ownership bias. I think the SEX looks the coolest, so there's a bit of bias there.
All listening was done with HD650s. The Pass was the least powerful, with the listening done at about 2 o'clock, while the other two were at 10 or 11 o'clock.
The T3 has the punchiest bass, but only by a hair. The SEX gets a bit flabby down low, but it's nice and round and euphonic. Surprisingly, the Pass goes deeper than the other two and was more effective at getting my groove on.
Another surprise: vocals were best on the SEX. More body, more soul.
The SEX fell down on detail. The T3 was noticeably better while the Pass was in a different league. This was by far the largest difference between the amps.
The Pass had a more expansive sound-stage while the other two were more similar than not. It wasn't so much that the Pass was wider or taller (although it might have been), but more that it felt like you could walk around in between the various bits.
The SEX was more fun than the T3, but if I was listening seriously I'd be annoyed by the loss of detail. The Pass consistently gave me goosebumps where the other two didn't. For me? The Pass without a moment's hesitation.
I compared it to 2 other DIY builds: a Bottlehead SEX with some modifications (no CCS) and a Torpedo 3 clone (with tube and output stage CCSes). They were all built by me, so no ownership bias. I think the SEX looks the coolest, so there's a bit of bias there.
All listening was done with HD650s. The Pass was the least powerful, with the listening done at about 2 o'clock, while the other two were at 10 or 11 o'clock.
The T3 has the punchiest bass, but only by a hair. The SEX gets a bit flabby down low, but it's nice and round and euphonic. Surprisingly, the Pass goes deeper than the other two and was more effective at getting my groove on.
Another surprise: vocals were best on the SEX. More body, more soul.
The SEX fell down on detail. The T3 was noticeably better while the Pass was in a different league. This was by far the largest difference between the amps.
The Pass had a more expansive sound-stage while the other two were more similar than not. It wasn't so much that the Pass was wider or taller (although it might have been), but more that it felt like you could walk around in between the various bits.
The SEX was more fun than the T3, but if I was listening seriously I'd be annoyed by the loss of detail. The Pass consistently gave me goosebumps where the other two didn't. For me? The Pass without a moment's hesitation.
Attachments
Or, more inexpensively, connect a 3W 68 ohm resistor from tip to sleeve, and another 3W 68 ohm resistor from ring to sleeve. A little box inline between 1/4" male stereo TRS plug and a 1/4" female stereo TRS jack, is one way to implement it quickly.
Now the load seen by the HPA is (Zout_HD650 InParallelWith 68R) = (300 parallel 68) = 55 ohms, which is the point exactly half way between the HE-6 and the AK701. And it doesn't cost hundreds of dollars to try the experiment.
Now the load seen by the HPA is (Zout_HD650 InParallelWith 68R) = (300 parallel 68) = 55 ohms, which is the point exactly half way between the HE-6 and the AK701. And it doesn't cost hundreds of dollars to try the experiment.
I'm mostly a two-channel guy, so the 650s are all I have in the way of cans. Mark's experiment looks like a good starting point.
I was also thinking of picking up either an Elex or LCD-2 (80 and 70 ohms)....
I was also thinking of picking up either an Elex or LCD-2 (80 and 70 ohms)....
The difference between a paralleled resistor and a low-impedance phone is the signal voltage level.
A 50R phone in general requires less voltage but more current than a 300R or 600R phone.
But it is still a fair comparison if you apply the same 55R (equivalent) to all 3 amps.
Then a high-bias amp starts to shine.
My DAO HP, e.g. has 300mA bias for the JFET buffer alone.
Patrick
A 50R phone in general requires less voltage but more current than a 300R or 600R phone.
But it is still a fair comparison if you apply the same 55R (equivalent) to all 3 amps.
Then a high-bias amp starts to shine.
My DAO HP, e.g. has 300mA bias for the JFET buffer alone.
Patrick
That'll make my choice easier.
Highly recommended (although they are quite heavy) 😉😉😉.